Smart RSS in Snapshot 1.0.420.4 +
I don't know if this might be useful for anyone but it was for me. I've been using Smart RSS extension (opera 15+ extension) since Vivaldi allowed extensions, but since Snapshot 1.0.420.4 the extension disappeared. When checking vivaldi://extensions it simply wasn't there, when trying to re-add the unpacked extension you'd get an error that read something like "cannot load "19": "images/icon19-arrow-orange". Well to fix it and get back Smart RSS (didn't lose any data by the way) you just have to add .png to that line in the manifest.json file which is located inside the unpacked extension folder, you can edit it with notepad++ and I guess also with any other text editor. For some reason it worked fine without the extension until this snapshot, at least for me, but it's easy to fix it. Greetings.